Apparatus for applying organic liquid coating to moving strip material



April 13, 1955 J. E. SCHNIERLEIN 3,177,847

APPARATUS FOR APPLYING ORGANIC LIQUID COATING TO MOVING STRIP MATERIALFiled Sept. 29. 1961 INVENTOR.

JOSEPH E. SCHNIERLEIN i 25 BY. izo 26 W L ATTORNEYS United States PatentO 3,177,847 APPARATUS FOR APPLYING ORGANIC LIQUFD COATING T MUVING STRIPMATERIAL Joseph E. Schnierlein, Allentown, Pa., assignor to NationalSteel Corporation, a corporation of Delaware Filed Sept. 29, 1961, Ser.No. 141,391

' 3 Claims. (Cl. 118407) This invention relates to coating apparatus andmore particularly to apparatus for applying organic coatings tocontinuously moving strip material.

Apparatus has been provided in the past for applying organic coatingsuch as paints and enamels to surfaces of continuously moving stripmaterial. However, it has not been possible with such apparatus toobtain extremely smooth coating of uniform controllable thicknessespecially when the surface of the strip material is irregular or whenthe strip material is of substantial width.

It is an object of the present invention to provide novel apparatuswhich makes it possible to apply extremely smooth organic coating ofuniform thickness to continuously moving strip material and overcome thelimitations of the prior apparatus.

The foregoing is accomplished by the provision of a novel arrangementfor applying liquid coating substance to moving strip material. Thenovel arrangement includes a polished cylindrical roll positioned inline contact with the moving strip material and rotated in a directionopposite to the direction of movement of the strip material, togetherwith means for applying measured quantities of liquid coating substanceto the roll so as to form precisionally a pool of liquid coatingsubstance extending trans versely of the strip material between theopposing surfaces of the strip material and the roller above the linecontact. This arrangement provides liquid application of the coatingsubstance to the strip material by action of the coating substanceitself as distinguished from the use of mechanical means for applying orleveling the coating substance, and results in extremely smooth coatingsirrespective of irregularities in the surfaces of the strip ma terialwhile making it possible to control the thickness of the coating to adegree and with uniformity heretofore unobtainable.

Other objects and features of the present invention will appear morefully from the following detailed description considered in connectionwith the accompanying drawing which illustrates one embodiment of theinvention.

In the drawing, in which similar refe ence characters denote similarelements through the several views:

FIGURE 1 is a diagrammatic presentation of a strip coating lineembodying principles of the present invention;

FIGURE 2 is a diagrammatic showing of a coating applicator constructedin accordance with the principles of the present invention;

FIGURE 3 is an elevational view, partly in section, of the coatingapplicator provided by the present invention, and

FIGURE 4 is a detailed view of a portion of the coating applicator shownin FIGURE 3.

With reference more particularly to FIGURE 1 of the drawings, a coatingline for applying organic coatings to moving strip material isdiagrammatically shown therein including a coil it of uncoated stripmaterial mounted on 3,177,847 Patented -Apr. 13, i965 "ice a suitableuncoiling mechanism not shown. Strip material withdrawn from the coilIll passes around guide roller 11 and upwardly along a substantiallyvertical pass and then around guide roller 12. The strip material uponits upward travel, as viewed in the drawing, along the sub stantiallyvertical pass, which is identified by reference numeral 13, moves pastcoating applicator 14 constructed in accordance with the presentinvention. As described in detail below, the coating applicator 14functions to apply a coating of organic substance to one side of thestrip material and the coated strip material after passing around roller12 enters a curing furnace 15 which may be provided with a plurality ofupper rollers 16 and a plurality. of lower rollers 17 to cause the stripmaterial to traverse a plurality of passes 18 upon moving through thefurnace. The furnace may be fired by any suitable means to maintain therequired temperature for curing the organic coating and strip materialhaving cured organic coating thereon leaves the furnace and is coiled ina coil 19 formed on a suitable coiling mechanism, not shown, whichfunctions to move the strip material through the line at the requiredrate of speed. Rollers which guide the strip material when coating isuncured, such as rollers 12 and at least certain of the rollers 15 and17 within the furnace, are designed to support the strip material insuch a manner as not to mar the coating. For example, the strip materialmay be supported by contact with the edges only of the strip material;rollers of the type shown in Patent 2,979,829 are suitable for thispurpose.

The coating applicator 14 is shown in more detail in FIGURE 2 andincludes a cylindrical roller 20 and a distributor 21 for transferringliquid coating substance to the roll 241 The roll 20 is of cylindricalform and is provided with a polished external surface and is preferablyconstructed of metal. As shown in FIGURE 3, shafts 22 and 23 areprovided at opposite ends of the roll Zil and the shafts 22 and 23 aresupported in bearing blocks 24 and 25, respectively, to rotatably mountthe roll 29 with its longitudinal axis lying in a horizontal plane. Thebearing blocks 24 and 25 are slidably mounted between pairs ofvertically spaced lateral guide members 26 and 27 supported by standards28 and 29. The feature of supporting the shafts of the roll 20 byslidably mounted bearing blocks makes it possible to adjust the lateralposition of the axis of rotation of the roll. The bearing blocks may belaterally adjusted by any suitable means such as by an arrangement asshown in FIGURE 4 including an elongated member 30 threadedly supportedin standard 28 and attached to a bearing block to permit rotation of themember 30 to thereby impart lateral movement to the bearing block. Theroll 20 is positively rotated by means of a variable speed drive 31coupled to the shaft 23 as indicated by broken line 32.

' The distributor 21 for liquid coating substance includes an elongatedhollow member 35 having closed ends to define an elongate'charnber 36for receiving liquid coating substance, the member may be of anydesirable crosssectional' shape. Liquid coating substance is supplied tothe chamber 35 by a variable capacity pump 37 connected to the chamber36 by a conduit 38 which may communicate with the chamber 36 along itslength or at one or both of its ends; the pump .37 being connected to asource of coating substance by conduit 39.' The distributor 21 alsoincludes an elongated feeder plate 40 joined to or merging from theunderside of the member and extending substantially throughout itslength. The wall of the elongated member 35 includes means forming anelongated slot 41 which extends longitudinally of the member 35substantially throughout its length and parallel to its longitudinalaxis. The slot 41 is located in the region of the merged or joined edgeof the feeder plate with the member 35 so that the slot 41 discharges oropens onto the upper surface 42 of the feed plate. The feeder plate 40extends from the right hand side of the member 35, as viewed in FIGURE2, and downwardly and terminates in a knife edge 43. An elongatedmetering blade 44 may be adjustably positioned by any suitable means,not shown, on the elongated hollow member 35 adjacent the elongated slot41 to regulate the quantity of coating material flowing through the slotonto the surface 42 of the feeder plate and the metering blade may beprovided with calibrated serrations on its metering edge 45 if desired.

The elongated hollow member 35 is provided with end supports and 51mounted in blocks 52 and 53, respectively, which are slidably mountedbetween lateral members 27 j and adjacent vertically spaced upperlateral members 54. The slidable blocks 52 and 53 each may be adjustedlaterally by any suitable means such as by an elongated threaded member55 shown in FIGURE 4.

In accordance with the principles of the present invention the roll 20is positioned relative to the strip material to establish line contactwith one surface of the strip material; preferably the line contact isdisposed in a hori zontal plane and for this purpose the strip materialmoves upwardly through the pass 13 with its edges lying in substantiallyvertical planes and the roll 20 rotates about a substantially horizontalaxis. The bearing blocks 24 and 25 are laterally adjustable to establishthe line contact relationship with one surface of the strip material. Asshown in.FIGURE 2, the distributor 21 is positioned relative to the roll20 so that the feeder plate 40 is inclined downwardly and in a directiontoward the roll 20 with its terminating edge 43 parallel to thelongitudinal axis of the roll 20 and closely spaced above the surface ofthe roll 20 in a vertical plane positioned between the strip materialand the axis of rotation of the roll 20. The required positioning of theterminating edge 43 of the feeder plate relative to the roll 20 may beaccurately established by adjusting the laterally movable blocks 52 and53. The angle of inclination of the feeder plate is such as to cause theliquid coating substance to flow under the influence of gravity from theslot 41 uniformly over the surface 42 and uniformly from the terminatingedge 43 onto the roll 20.

As mentioned above, the strip material, upon moving through the pass 13,moves vertically upwardly as indicated by arrow A. In accordance withthe principles of the present invention the polished surface on the roll20 moves in a direction opposite to the direction of movement of thestrip material and thus the roll 20 is rotated by the variable speeddrive 31 in a clockwise direction as indicated by arrow B; the movementof the polished surface of the roll 20 being small as compared to themovement of the strip material.

In operation, the variable capacity pump 37 is adjusted to supply asufficient rate of flow of liquid coating substance to the chamber 36 byway of the conduit 38 to maintain liquid coating substance within thechamber 36 under constant pressure so that liquid coating substanceuniformly flows past the metering end 45 throughout the length of theslot 41 and uniformly over the inclined surface 42 and from the edge 43onto the outer surface of the roll 20. Clockwise rotation of the roll 20moves the liquid coating substance downwardly and a pool of liquidcoating substance is formed between opposing surfaces of the stripmaterial and the outer surface of the roll 20 immediately above the linecontact between the roll and the strip material. The pool of coatingsubstance extends throughout the width of the strip material andmovement of the strip material past the pool 60 results in coatingsubstance being applied uniformly to the strip material throughout itswidth.

The thickness of the coating applied to the strip material is a functionof a number of variables including the speed of the strip material, thespeed of rotation of the roll 20, and the rate of flow of liquid coatingsubstance downwardly on the inclined surface 42 which in turn dependsupon the size of the slot 41 and the output of the variable capacitypump 37. All of the foregoing factors relate to the size of the pool 60and the size of the pool 60 relates directly to the thickness of thecoating applied to the strip material inasmuch as the coating is appliedto the strip material as a consequence of the strip material moving pastthe pool 60 of liquid coating composition. The feature of rotating theroll 20 in a direction opposite to the direction of movement of thestrip material also makes it possible to control with great accuracy thethickness of the applied coating. The roll 20 performs a wiping functionand moves liquid coating substance from the pool 60 past the linecontact with the strip material. The quantity of liquid coatingsubstance removed from the pool 60 increases as the speed of rotation ofthe roll 20 increases and thus the thickness of the applied coating maybe regulated by varying the speed of rotation of the roll 20. Liquidcoating substance moved by the roll 20 past the line contact is movedaway from the strip material by the roll 20 and a doctor blade 61 isprovided for removing such substance to provide a clean surface forreceiving liquid coating composition discharged from the edge 43.

The feature of the present invention of liquid application of coatingsubstance to the strip material unexpectedly obtains extremely smoothcoatings even when the surface being coated is rough. It is believedthat when the strip material moves. into contact with the pool 60 theliquid coating substance is forced into contact with the surface of thestrip material due at least in part by the action of thecounter-rotating roll 20 and all irregularities in the surface of thestrip material are filled with liquid coating substance. Thereafter,when the strip material moves out of contact with the pool 60 liquidcoating substance tends to move with the strip material but the liquidcoating substance will shear with one part remaining on the stripmaterial as the coating and another part returning to the pool. Theplane in which this shearing action takes place will depend upon anumber of factors including characteristics of the coating substance andthe period of contact of the strip material with the pool 60 but in anyevent the shearing action takes place in a plane displaced from thesurface of the strip material and is planar and uninfluenced by surfaceirregularities. While the foregoing is a theoretical explanation it isknown that use of the applicator provided by the present invention makesit possible to obtain extremely smooth coatings uninfluenced byunderlying surface irregularities as distinguished from coatingsproduced by prior apparatus in which films of coating of substantiallythe same thickness are applied uniformly to the surface of the stripmaterial.

In the arrangement shown in FIGURE 2 of the drawings the roll 20 is inline contact with the strip material which moves from a region below theroll 20 upwardly along a path perpendicular to a horizontal planepassing through the'longitudinal axis of the roll 20 to a region abovethe roll 20. While this is the preferred relationship it is to beexpressly understood that the path of the strip material need not beperpendicular to a plane passing through the horizontal axis of the rollbut may be inclined with respect to such a horizontal plane either tothe right or the left from the pass 13 shown in FIGURE 2. With thearrangement shown in FIGURE 2 inclination of the path of the stripmaterial in a direction toward the distributor 21 is of course limitedby the physical location of the distributor with respect to the rollerhowever inclination of the path of the strip material in the oppositedirection is not so limited. While in most instances it may be preferredto practice the invention with the strip material moving upwardly alonga vertically disposed pass as shown in FIGURE 2, it may be desirable incertain cases to incline the plane of the path of the strip material.One reason for practicing the present invention with the plane of thestrip material inclined would occur in instances where the coatingsubstance has high fluidity or low rate of adherence or both. In anyevent, in order to practice the present invention it is necessary toestablish line contact between the outside surface of the roll 20 andthe surface of the strip material being coated with the angularrelationship of the path of the strip material and a horizontal planepassing through the longitudinal axis of the roll being such so that apool of coating substance of proper size to produce the desired coatingis maintained between opposite surfaces of the strip material and theroll above the line contact. Although the cavity defined by oppositesurfaces of the roll 20 and the strip material above the line contact isopen ended the pool 60 is uniform throughout the usable width of thestrip material since the cross-sectional area of the pool is extremelysmall relative to its length and since the pool is fed uniformly withliquid coating substance throughout its length.

The following are examples of actual operation of a continuous stripcoating line embodying the principles of the present invention:

Example 1 Strip Material.-Steel strip with hot dipped galvanizedspangled coating Gage: 0.0217 inch Width of strip: 43% inches Width ofcoated product: 42 inches Coating MateriaZ.Vinyl paint Viscosity: 34seconds Zahn No. 1 cup Temperature: 130 F. Speed of strip material: 35feet per minute Speed of rotation roll: 1 revolution per minute Flow ofcoating substance: .24 gal/min. Film thickness: 0009-001 Example 11Strip MateriaL-Sheet strip coated with hot dipped galvanized coatingGage: 0.0217 inch Width of strip: 30% inches Width of coated product: 29inches Coating MaieriaL-Vinyl paint Viscosity: 32 seconds Zahn No. 1 cupTemperature: 130" F. Speed of strip material: 47 feet per minute Speedof rotation of roll: 3 revolutions per minute Flow of coating substance:.20 gal./ min. Film thickness: .0007

The coated strip material produced from the foregoing examples wasextremely smooth with very good adhesion and flexibility and excellentresults were obtained from Zuhr, cone and mandrel tests.

It is to be expressly understood that the principles of the presentinvention may be employed to coat both sides of the strip material upona single pass through a processing line. This may be accomplished byproviding apparatus similar to the arrangement shown in FIGURE 2 foroperation upon the other side of the strip material. Although, asdiscussed above, the present invention makes it possible to produceextremely smooth coating of precisional thickness it is to be understoodthat a leveler '6 roller, such as roller 62, may be used in connectionwith the principles of the present invention such as when extremelythick coatings are desired.

Although only one embodiment of the invention has been disclosed anddescribed herein, it is to be expressly understood that various changesand substitutions may be made therein without departing from the spiritof the invention as well understood by those skilled in the art.Reference therefore will be had to the appended claims for a definitionof the limits of the invention.

What is claimed is:

1. In a coating apparatus, a smooth surface elongated cylindrical roll,means rotatably mounting the roll with its longitudinal axis disposed ina horizontal plane, means moving strip material along a path from aregion located below the roll upwardly past the roll with one surface ofthe strip material in line contact with the roll to a region locatedabove the roll, the path lying in a plane disposed in angularrelationship with a horizontal plane passing through the longitudinalaxis of the roll, means applying liquid coating substance to the rollalong a length of the roll at least corresponding to the width of thestrip material, means rotating the roll in a direction opposite to thedirection of movement of the strip material to move liquid coatingsubstance applied to the roll in a direction toward the one surface ofthe strip material, and means controlling the speed of rotation of theroll and the quantity of coating substance applied to the roll inaccordance with the speed of the strip material to maintain a pool ofliquid coating substance extending along the width of the strip materialin the space defined by the portion of the one surface of the stripmaterial above the line contact and the opposing surface portion of theroll.

2. In a coating apparatus, a smooth surface elongated cylindrical roll,means rotatably mounting the roll with its longitudinal axis disposed ina horizontal plane, means moving strip material along a path from aregion located below the roll upwardly past the roll with one surface ofthe strip material in line contact with the roll to a region locatedabove the roll, the path lying in a plane disposed in angularrelationship with a horizontal plane passing through the longitudinalaxis of the roll, an elongated hollow member defining a chamber and anelongated slot communicating with the chamber, an elongated downwardlyinclined feeder plate extending from the slot to the roll, means forfeeding liquid coating substance to the chamber, means rotating the rollin a direction opposite to the direction of movement of the stripmaterial to move liquid coating substance applied to the roll in adirection toward the one surface of the strip material and form a poolof liquid coating substance extending along the width of the stripmaterial and confined by the portion of the one surface of the stripmaterial above the line contact and the opposing surface portion of theroll, and means controlling the speed of rotation of the roll and thequantity of coating substance applied to the roll in accordance with thespeed of the strip material to apply coating of predetermined thicknessto the one surface of the strip material.

3. In a coating apparatus, a smooth surface elongated cylindrical roll,means rotatably mounting the roll with its longitudinal axis disposed ina horizontal plane, means moving strip material along a path from aregion located below the roll upwardly past the roll with one surface ofthe strip material in line contact with the roll to a region locatedabove the roll, the path lying in a plane disposed in angularrelationship with a horizontal plane passing through the longitudinalaxis of the roll, an elongated hollow member defining a chamber and anelongated slot communicating with the chamber, and elongated downwardlyinclined feeder plate extending from the slot to the roll, means forfeeding liquid coating substance to the chamber, the elongated feederplate terminating in a plane intermediate the path of the strip materialand a vertical plane passing through the axis of rotation of the roll,means rotating the roll in a direction opposite to the direction ofmovement of the strip material to move liquid coating substance appliedto the roll in a direction toward the one surface of the strip materialand form a pool of liquid coating substance extending along the width ofthe strip material and confined by the portion of the one surface of thestrip material above the line contact and the opposing surface portionof the roll, and means controlling the speed of rotation of the roll andthe quantity of coating substance applied to the roll in accordance withthe speed of the strip material to apply coating of predeterminedthickness to the one surface of the strip material.

ReferencesCited by the Examiner UNITED STATES PATENTS Hodgman 118-407 XFaulkner 1 1 18-407 Obenshain et a1 118-259 X Cook et a1 118419 XHornbostel 1 18 Uhleen 118-118 X Stickel 1 18-407 Colwill et a1 118-259X RICHARD D. NEVIUS, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,177,847 April 13, 1965 Joseph E. Schnierlein It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as corrected below.

Column 2, line 23, for "rollers" read roller column 3, line 10, for"feed" read feeder column 5, line 44, for "Speed of rotation ro1l:" readSpeed of rotation of roll: column 6, line 70, for "and" read an Signedand sealed this 28th day of September 1965.

(SEAL) Auest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. IN A COATING APPARATUS, A SMOOTH SURFACE ELONGATED CYLINDRICAL ROLL,MEANS ROTATABLY MOUNTING THE ROLL WITH ITS LONGITUDINAL AXIS DISPOSED INA HORIZONTAL PLANE, MEANS MOVING STRIP MATERIAL ALONG A PATH FROM AREGION LOCATED BELOW THE ROLL UPWARDLY PAST THE ROLL WITH ONE SURFACE OFTHE STRIP MATERIAL IN LINE CONTACT WITH THE ROLL TO A REGION LOCATEDABOVE THE ROLL, THE PATH LYING IN A PLANE DISPOSED IN ANGULARRELATIONSHIP WITH A HORIZONTAL PLANE PASSING THROUGH THE LONGITUDINALAXIS OF THE ROLL, MEANS APPLYING LIQUID COATING SUBSTANCE TO THE ROLLALONG A LENGTH OF THE ROLL AT LEAST CORRESPONDING TO THE WIDTH OF THESTRIP MATERIAL, MEANS ROTATING THE ROLL IN A DIRECTION OPPOSITE TO THEDIRECTION OF MOVEMENT OF THE STRIP MATERIAL TO MOVE LIQUID COATINGSUBSTANCE APPLIED TO THE ROLL IN A DIRECTION TOWARD THE ONE SURFACE OFTHE STRIP MATERIAL, AND MEANS CONTROLLING THE SPEED OF ROTATION OF THEROLL AND THE QUANTITY OF COATING SUBSTANCE APPLIED TO THE ROLL INACCORDANCE WITH THE SPEED OF THE STRIP MATERIAL TO MAINTAIN A POOL OFLIQUID COATING SUBSTANCE EXTENDING ALONG THE WIDTH OF THE STRIP MATERIALIN THE SPACE DEFINED BY THE PORTION OF THE ONE SURFACE OF THE STRIPMATERIAL ABOVE THE LINE CONTACT AND THE OPPOSING SURFACE PORTION OF THEROLL.